1. Field of the Invention
This invention relates to a recording material such as a light-sensitive mateiral, a heat-sensitive material and a pressure-sensitive material, and more particularly to a recording material containing a leuco dye.
2. Description of Prior Art
In various recording materials including light-sensitive, heat-sensitive and pressure-sensitive materials, a leuco dye is frequently used as a color image forming substance. In leuco dye, which is also referred to as a redox dye, develops a color on contact with an acid color developer.
The leuco dye is generally contained in microcapsules which are dispersed in a recording material. In an image forming process, the microcapsules are broken by external energy such as pressure and/or heat so that the dye comes into contact with the acid color developer which is arranged outside of the microcapsules in the recording material.
Conventional leuco dyes which develop yellow are described in Japanese Patent Publication Nos. 45(1970)-4698, 50(1975)-24646, 51(1976)-27169 and 53(1978)-9127 and Japanese Patent Provisional Publication No. 49(1974)-4480. It is described in these Publications that most of the leuco dyes are advantageously used in a pressure-sensitive material. In addition to the pressure-sensitive material, leuco dyes are also employed in other recording materials, such as a light-sensitive mateiral and a heat-sensitive material.
Examples of the light-sensitive material include a light-sensitive material comprising a light-sensitive layer containing silver halide, a reducing agent and a polymerizable compound provided on a support as well as conventional silver salt photo-sensitive materials. The light-sensitive material containing silver halide, a reducing agent and a polymerizable compound is described in U.S. Pat. No. 4,629,676 and Japanese Patent Provisional Publication Nos. 61(1986)-183640, 61(1986)-188535, 61(1986)-228441, 61(1986)-243449, 61(1986)-260241, 61(1986)-275742 and 61(1986)-278849. Further, the light-sensitive material containing a leuco dye which developes yellow is described in Japanese Patent Application Nos. 61(1986)-133091 and 61(1986)-133092.